Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view showing a first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is a front view showing a second image thereof;

FIG. 3 is a front view showing a third image thereof;

FIG. 4 is a front view showing a fourth image thereof;

FIG. 5 is a front view showing a fifth image thereof;

FIG. 6 is a front view showing a sixth image thereof;

FIG. 7 is a front view showing a seventh image thereof;

FIG. 8 is a front view showing an eighth image thereof;

FIG. 9 is a front view showing a ninth image thereof; and,

FIG. 10 is a front view showing a tenth image thereof.

The appearance of the transitional graphical user interface sequentially transitions between the images shown in FIGS. 1-10. The process or period in which one image transitions to another forms no part of the claimed design. The broken line showing of the display screen in all views forms no part of the claimed design. The other broken lines show portions of the transitional graphical user interface—the graphic elements and text—that form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 